com.antelmann.util
Class UniversalComparator

java.lang.Object
  com.antelmann.util.UniversalComparator

All Implemented Interfaces:

Comparator<Object>

public class UniversalComparator
extends Object
implements Comparator<Object>

The UniversalComparator is useful as a default if no other more specific sorting strategy is present. Its Collator first tries to order the objects by their natural order - if applicable (except for Strings, which will be sorted with a default Collator). If that fails, the objects will be sorted based on their toString() value using the embedded instance of a Collator. Also, this class gracefully handles null values.

Since:

6/2/06

Author:

Holger Antelmann

See Also:

Collator

Constructor Summary

UniversalComparator()
uses the default Collator instance

UniversalComparator(boolean caseSensitive)
uses no Collator but direct String comparison instead

UniversalComparator(Collator collator)
if a null value is given, String comparison is used instead of a collator

Method Summary

static <T> Comparator<T>	combine(Comparator<? super T> c1, Comparator<? super T> c2)
int	compare(Number n1, Number n2)
int	compare(Object o1, Object o2) null values are accepted and are sorted before a non-null value
int	compare(String o1, String o2)
Collator	getCollator() provides access to the embedded collator (which may be null); its standard instance is the default value.
static UniversalComparator	getDefaultInstance() returns one global default instance, which uses the default Collator instance by default
boolean	isCaseSensitive() if true, the String comparison (if it applies) is case sensitive (false is the default).
static <T> Comparator<T>	reverse(Comparator<T> c) a utility method for convenience that simply reverses the given ordering
Comparator<Object>	reversed()
void	setCaseSensitive(boolean flag) if set to true, the String comparison (if it applies) is case sensitive.
void	setCollator(Collator collator) allows to change the default collator in use; if set to null, the String comparison is used directly without a Collator.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Comparator

equals

Constructor Detail

UniversalComparator

public UniversalComparator()

uses the default Collator instance

UniversalComparator

public UniversalComparator(boolean caseSensitive)

uses no Collator but direct String comparison instead

UniversalComparator

public UniversalComparator(Collator collator)

if a null value is given, String comparison is used instead of a collator

Method Detail

getDefaultInstance

public static UniversalComparator getDefaultInstance()

returns one global default instance, which uses the default Collator instance by default

getCollator

public Collator getCollator()

provides access to the embedded collator (which may be null); its standard instance is the default value.

setCollator

public void setCollator(Collator collator)

allows to change the default collator in use; if set to null, the String comparison is used directly without a Collator.

See Also:

String.compareTo(String)

isCaseSensitive

public boolean isCaseSensitive()

if true, the String comparison (if it applies) is case sensitive (false is the default). Note that this option only applies if the collator of this instance is null!

setCaseSensitive

public void setCaseSensitive(boolean flag)

if set to true, the String comparison (if it applies) is case sensitive. Note that this option only applies if the collator of this instance is null!

compare

public int compare(String o1,
                   String o2)

compare

public int compare(Number n1,
                   Number n2)

compare

public int compare(Object o1,
                   Object o2)

null values are accepted and are sorted before a non-null value

Specified by:

compare in interface Comparator<Object>

reversed

public Comparator<Object> reversed()

reverse

public static <T> Comparator<T> reverse(Comparator<T> c)

a utility method for convenience that simply reverses the given ordering

combine

public static <T> Comparator<T> combine(Comparator<? super T> c1,
                                        Comparator<? super T> c2)